I've just purchased some NICs & they contain a setting to enable/disable Rx & Tx flow control. What is this flow control, and what are the benefits/disadvantages of setting it?

While I'm on the subject, I have a linux router/gateway (using the smoothwall distro). I have to set the NIC for the internal network to half duplex - am I alright to set the NIC for the internet to full duplex, or do all nics in the same box need to be set to the same duplex?

I would set all the Nics to run at auto. This way everything runs the way it is supposed to and you wont have any problems. If the hardware supports it, then it will run it. Dont force it.

Flow control is good to use. It will help elimate collitions on the network, I have my flow control on and I get top speed. So it wont hurt.
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Maondas
(Premium)
Joined 09-19-2002
Location: Hoboken, NJ

Enabling/Disabling Tx/Rx flow control on a NIC will have almost no visible effect. They will typically only come in to play at very high (100Mbps) speed bursts that are sustained for a long period of time. Leave it in the default mode, you won't notice a difference.

You are perfectly fine to have one NIC in a computer set at full duplex and one set at half, and you should do so if the networks you are connected to require that setup. Personally I avoid auto-detect because it is not 100% reliable, and a duplex mismatch can *seriously* impact performance.